Motor cut out on me -- Johnson/Suzuki 2005 115hp 4 stroke

Joined
Feb 8, 2023
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66
I have a 2005 Johnson (Suzuki) 115hp 4 stroke with 540 hours

Two weeks ago I was out on the boat and cranked the motor up after fishing a spot -- pushed the throttle down to get up on plane and the outboard bogged down - I came off the throttle for 10 seconds and then pushed it back down and it operated normal for the rest of the day.

I did the plugs, lower unit oil, gearcase oil, oil filter, fuel filter last weekend.

Today when I was out on the boat the outboard ran flawless for a couple hours of fishing lots of starting and stopping. Towards the very end of my day I cranked up the motor to change locations -- I got on the throttle quickly to get on plane and ran about a hundred yards and then the motor cut out.

I went to crank it back up and it cranked up for about 1 second and shut off. I tried again and it didn't want to start. I figured it was maybe a fuel line issue so I pulled the fuel connecter and held the bead down and primed the bulb -- fuel came pouring out with each pump.

I connected the fuel back up and tried to crank it again -- it didn't want to crank up.

I started the slow journey to the boat ramp with my trolling motor. About 15 minutes later -- I figured I would try again and this time it cranked right up - I slowly put it in gear and slowly gave it throttle. The outboard performed like normal all the way to the ramp.

Once I got close to the ramp -- I figured I would turn it off and see if it would crank...I did that a few times and the motor was operating normal.

When I got home I did a compression test and all 4 cylinders were at 175.
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All that said, I am wondering what your thoughts are on this. Any ideas?

To me it sounds like a fuel issue -- but if it was a fuel issue why would it crank back up later?

I am going to replace the RACOR filter on my boat tomorrow just for good measure.
 

stresspoint

Lieutenant Junior Grade
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Sep 19, 2022
Messages
1,029
it sounds from the description you have given you may have an issue with the fuel pressure regulator.

these issues can be a bit hard to trace. However best guess is pressure reg failing to keep up.

vapor lock can happen on these motors when fuel pressure is low either from a failing fuel pump ?? or failing regulator

if you can , ?? , hook it up to SDS and see if any irregularity's in injector pressure (injector drop test) after it has sat when hot.

one remedy is to allow the motor to idle a bit before punching it WOT after it has sat.
 
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99yam40

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I am surprised he did not pump the primer bulb to see if that helped when the motor would not start up.

does that motor have a water cooled fuel cooler that might be restricted/plugged
 
Joined
Feb 8, 2023
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great feedback here gents

I actually did pump the primer bulb a few times but it didn’t seem to make a difference

Not sure if the outboard is water cooled fuel cooler - I’m not sure what even is. Guess I’ll need to read up

Fuel pump seems to be fine but I’ll look into the fuel pressure reg.

Any and ideas are welcome. I’d love to figure it out. I’ll report my findings
 

99yam40

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was the primer bulb firm or were you able to push fuel into the VST when you were priming?
if no fuel in the VST the pump has nothing to pressure up the rail and the pump is cooled and lubed by the fuel being pumped.
not having fuel in there is not good for the pump
 
Joined
Feb 8, 2023
Messages
66
was the primer bulb firm or were you able to push fuel into the VST when you were priming?
if no fuel in the VST the pump has nothing to pressure up the rail and the pump is cooled and lubed by the fuel being pumped.
not having fuel in there is not good for the pump
Primer bulb was not firm - I was able to push fuel into the VST when priming
 

99yam40

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Should have kept pumping the bulb until the VST was full to keep the pump from running without fuel.
need to figure out what is needed to keep the Fuel in VST from boiling away
 
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